ขอบสอบถามเรื่อง Loop ใน Listview หน่อยครับ คำนวณ Row แรกอย่างเดียวไม่คำนวณตามไอดีที่ระบุ

 Private Function FindSubItem(ByVal lv As ListView, ByVal SearchString As String) As Boolean
        Dim idx = (From c In ListView1.Columns Where c.Text = "รหัสสี" Select c = c.Index).First()
        For Each itm As ListViewItem In lv.Items
            If itm.SubItems(idx).Text = SearchString Then Return True
        Next
        'Return False
    End Function

  Try
            Dim articlecheck As String = txtMixID.Text
            If FindSubItem(ListView1, articlecheck) = True Then


                For Each itms As ListViewItem In ListView1.Items
                    If txtMixID.Text = articlecheck Then
                        Dim tmpAmount As Integer = 0
                        Dim tmpce As Integer
                        tmpAmount = itms.SubItems(3).Text
                        tmpce = CInt(tmpAmount + Val(txtAmountPay.Text))
                        itms.SubItems(3).Text = CStr(tmpce)
                        Exit Sub
                    End If
                Next


                For i = 0 To ListView1.Items.Count - 1
                    If txtMixID.Text = articlecheck Then
                        Dim tmpAmount As Integer = 0
                        'Dim Math As Double
                        Dim tmpce As Integer
                        'Dim TotalMath As Double
                       
                        tmpAmount = CInt(CDbl(ListView1.Items(i).SubItems(3).Text))
                        tmpce = CInt(tmpAmount + Val(txtAmount.Text))
                        ListView1.Items(i).SubItems(3).Text = CStr(tmpce)
                        Exit Sub
                    End If
                Next
            Else
                Dim arr As String() = New String(5) {}
                Dim itm As ListViewItem
                arr(0) = txtMixID.Text
                arr(1) = txtProductName.Text
                arr(2) = txtPrice.Text
                arr(3) = txtAmountPay.Text
                arr(4) = CInt(txtBalance.Text) - CInt(arr(3)) 'Balance
                arr(5) = CDbl(txtPriceSpec.Text) * CInt(txtAmountPay.Text)
                itm = New ListViewItem(arr)
                ListView1.Items.Add(itm)
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try